The present invention relates to an air conditioning apparatus which utilizes a ceiling space defined by a double ceiling as a supply chamber.
A multi-storied building generally accommodates slabs used as the floors of upper stories and double ceilings constructed of ceiling boards lined on the lower surfaces of the slabs. In the space defined by the double ceilings have been arranged lights, alarms, electric cords for broadcasting, and ducts for an air conditioner. However, when ducts for coupling the air conditioner with air diffusers open at a ceiling board have been arranged in the ceiling space defined by the double ceilings, large expense and long construction times have been required to install the piping works of the ducts. When beams and girders are depended from the slabs, the ducts are passed through the lower portion of the beams. Therefore, this allows a wide space between the slabs and the ceiling boards, resulting in a tall building with relatively low ceiling heights in each room.
From the above-described reasons, it has been proposed not to arrange such ducts in the ceiling space defined between the slabs and the ceiling boards but to utilize the ceiling space directly as a supply chamber. For example, Japanese Patent Publication No. 24,726/1978 disclosed a technique for utilizing a ceiling space defined by double ceilings as a supply chamber.
The cool air delivered from an air conditioner is introduced into a supply chamber of the ceiling space, and is subsequently supplied to rooms through a plurality of air diffusers. In this case, the exhaust air pressure of the air diffuser in the vicinity of the air conditioner (on the upstream side) is higher than that of the air diffuser farther from the air conditioner (on the downstream side), so that the air distribution thus becomes unbalanced. Accordingly, the temperature distribution in the room may become unbalanced. In order to prevent such drawbacks, the above-mentioned patent announcement disclosed the installation of motor-driven blowers at the respective air diffusers. These blowers were controlled by a controller such as a variable voltage device for controlling the rotating speeds of the respective blowers, thereby equalizing the temperature distribution in the room.
However, a blower can generally vary the quantity of air emitted when the pressure on the upstream side of a propeller is varied, even if the rotating speed of the blower is maintained constant. In general, the air pressure in the vicinity of the air conditioner is higher than that farther from the air conditioner in the supply chamber. Thus, when the rotating speeds of the respective blowers are equal, the blowing quantities of the respective blowers become irregular. Therefore, it is necessary to control the rotating speeds of the respective blowers so as to obtain uniform temperature distribution in the room. However, when the blowing quantity of one blower is varied, the entire air pressure distribution in the supply chamber will vary. Accordingly, other blowers should likewise be controlled. In this manner, when the blowing quantities of all the blowers have been eventually equalized, all the blowers would be controlled in a plurality of stages, which would require an extremely complicated control mechanism.